The Mediterranean fruit fly (Medfly,Ceratitis capitata) is a major problem for commercial orchards and householders alike, attacking more than 250 types of fruits, including citrus, apricots, nectarines, peaches, mangoes, apples and pears. The female medfly ‘stings’ fruits as she lays her eggs, making them vulnerable to infection and rot. Medfly’s versatility in the variety of crops it targets means that it is a pervasive threat all year round that requires intense insecticide control to prevent infestation. In Australia and the Americas it is also an invasive pest. The medfly is difficult to control by conventional methods, so new methods of pest control are needed that are both effective and environmentally friendly.

Traditionally medfly has been controlled by the application of insecticides. – In some places this has been achieved through orchard hygeine and by spraying orchards and treating fruit post-harvest with insecticides. Recently two key insecticides for medfly management – dimethoate and fenthion – were suspended by Australian authorities. This has left growers with fewer tools to protect their fruit crops against the medfly pest, so new options are needed, especially those that can be part of an Intergrated Pest Manamgent (IPM) approach for more environmentally friendly and sustainable agriculture.

The Department of Agriculture and Food in Western Australia (DAFWA) are currently investigating options for new and improved control of medfly. One such approach is the Sterile Insect Technique (SIT) where insects are sterilised by radiation prior to release over orchards. By mating with pest females, they reduce the number of pest flies in the next generation. Oxitec’s approach is a type of SIT that uses a self-limiting gene instead of radiation to reduce the number of pest offspring.

Benefits of Oxitec’s approach

Oxitec is an award-winning pioneer in insect pest control with an approach that is both effective and environmentally friendly. We genetically engineer insects to use them as a tool to control populations of their own species.

Studies in the laboratory and greenhouse cages have shown that Oxitec medfly can be very effective at reducing pest medfly populations. For example, in cage studies the pest populations were effectively controlled within 12 weeks.1

The approach is toxin-free and does not harm beneficial predators or insects.

The male flies only mate with their own species so other species are not directly affected. Also as this approach is based on preventing reproduction it is self-limiting in the environment

Reducing reliance on insecticides will support more sustainable agriculture and help beneficial insects, like bees, to thrive.

How the Oxitec Medfly (OX3864A) works

Oxitec male flies are released to mate with female flies of their own species. They pass on a ‘self-limiting’ gene that prevents the female offspring from reaching adulthood so they cannot ‘sting’ fruit crops or reproduce. This shrinks the pest population in the release area. The Oxitec medflies also have a fluorescent marker (DsRed2) to distinguish the Oxitec flies from the pests. This colour marker is used to monitor control of the pest population.

Next steps

The Oxitec Medfly has been evaluated in laboratory and greenhouse studies in the UK, Austria, Greece and Brazil.

Oxitec medfly has also been approved for outdoor trials in Brazil.

In Australia, DAFWA are planning a glasshouse evaluation of Oxitec medfly to evaluate how easily they can be produced and how well Australian female pest medflies mate with Oxitec males.